/Engine/Plugins/Developer/AnimationSharing/Source/AnimationSharing/Public/AnimationSharingManager.h
Retrieves a blend instance, this could either mean reusing an already in progress one or a brand new one (if available according to scalability settings) returns an index into OnDemandInstances array or INDEX_NONE if unable to setup an instance
uint32 SetupOnDemandInstance ( uint8 StateIndex )